19 And a certain scribe came and said to him: Master, I will follow thee whithersoever thou shalt go.

20 And Jesus saith to him: *The foxes have holes, and the birds of the air nests: but the son of man hath not where to lay his head.

21 And another of his disciples said to him: Lord, permit me first to go, and bury my father.

22 But Jesus said to him: Follow me, and let the dead bury their dead.

First, we should understand that the primary reference here is to spiritual life and death: in following Christ, this man would be on the path to eternal life, whereas he would be leaving behind those who were spiritually dead. Even so, while for most of us the command to honor father and mother includes providing for their burial, there are some souls who are called to a vocation in which they leave behind their families for the sake of the Kingdom--e.g., hermits and cloistered religious. Finally, it may not be that the parent was already dead but the man was asking that he not leave parents immediately, but delay until such time that his father had passed.